Mulvaney says "I don't want it, Mr. President" and Trump says "how about just trying it out...say Acting COS?" "You'll be doing the country and me an immense favor."
"Whaddya say, Mick?"
Mulvaney: "Oh, heck...okay, Mr. President. What the hell."
Trumps got his hooks into him. He'll most likely relent and accept the job permanently.
Trump's an operator.
Acting as opposed to sitting on his ass.